java中json格式怎么写 java json数据格式

 1.Json的格式

json 是一种与语言无关数据交换的格式，作用：使用ajax进行前后台数据交换，移动端与服务端的数据交换。

json是JS的原生内容，也就意味着JS可以直接取出json对象中的数据。

2.Json规则

1）映射用冒号（“：”）表示。名称:值

2）并列的数据之间用逗号（“，”）分隔。名称1:值1,名称2:值2

3）

   4）

         [

           {名称1:值,名称2:值2},

           {名称1:值,名称2:值2}

         ]

5）元素值可具有的类型：string, number, object, array, true, false, null

json有两种格式：

1）对象格式：{“key1”: obj,“key2”: obj,“key3”: obj...}

2)  数组格式：[obj,obj,obj...]

例：

User对象

{"userName" : "zhangsan","userAge" : "20","passWord" : "123456","addr":"北京"，"acount":{"money":"3333","time":"2018-08-22"}}

 

List<Product>

[{"pId":"10","pName":"魅族16","pPrice":"3500"},{"pId":"12","pName":"魅族17","pPrice":"3500"},{"pId":"13","pName":"魅族18","pPrice":"3700"}...]

 

注意：对象格式和数组格式可以嵌套。

          json的key是字符串，value是Object。

 

对象格式

<script language="JavaScript">

      /**

       * 案例一

       *  {key:value,key:value}

       * 

       * class Person{

       *      String firstName = "张";

       *    String lastName = "三丰";

       *    Integer age = 100;

       * }

       *

       * Person p = new Person();

       * System.out.println(p.firstName);

       */

      

       var person = {"firstName":"张","lastName":"三丰","age":100};

      //取出firstName

      alert(person.firstName);

      //取出laetName

    alert(person.lastName);

            

      //取出age

      alert(person.age);

      

  </script>

 

数组格式

<script language="JavaScript">

      /**

       * 案例二

       *  [{key:value,key:value},{key:value,key:value}]

       * 

       */

      

      var persons = [{"firstName":"张","lastName":"三丰","age":100},{"firstName":"李","lastName":"三丰","age":200},{"firstName":"马","lastName":"三丰","age":300}]

      

      //取出firstName == "李"

      alert(persons[1].firstName);

      

 

      </script>

 

对象中有数组

<script language="JavaScript">

   /**

       * 案例三

       * {

       *   "param":[{key:value,key:value},{key:value,key:value}]

       * }

       * 

       * 

       */

       var json = {

                   "baobao":[

                             {"name":"小双","age":22,"addr":"扬州"},

                             {"name":"小茹","age":22,"addr":"苏州"},

                             ("name":"小青","age":22,"addr":"徐州")

                             ]

       };

       //取name == 小茹

       alert(json.baobao[1].name);

  </script>

 

对象中多数组

<script language="JavaScript">

   /**

       * 案例四

       * {

       *   "param1":[{key:value,key:value},{key:value,key:value}],

       *   "param2":[{key:value,key:value},{key:value,key:value}],

       *   "param3":[{key:value,key:value},{key:value,key:value}]

       * }

       * 

       * 

       */

       var json = {

                   "baobao":[

                             {"name":"小双","age":22,"addr":"扬州"},

                             {"name":"小茹","age":22,"addr":"苏州"},

                             ("name":"小青","age":22,"addr":"徐州")

                             ],

                   "haohao": [

                                   {"name":"小爽","age":22,"addr":"南京"},

                                   {"name":"小洁","age":25,"addr":"苏州"},

                                   ("name":"小青","age":24,"addr":"徐州")

                                   ]   

       };

       //取"小洁"

       alert(json.haohao[1].name);

  </script>

 

 

混合嵌套 

<script language="JavaScript">

      /**

       * 案例五

       * {

       *   "param1":"value1",

       *   "param2":{},

       *   "param3":[{key:value,key:value},{key:value,key:value}]

       * }

       * 

       * 

       */

       var json = {

            "key1":"value1",

            "key2":{"firstName":"赵","lastName":"三丰","age":100},

            "key3": [{"firstName":"张","lastName":"三丰","age":100},{"firstName":"李","lastName":"三丰","age":200},{"firstName":"马","lastName":"三丰","age":300}]
   //取"赵"

       alert(json.key2.firstName);

      

      

      

  </script>
            

       };